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Apr
03

Pro Track Test- part 1 & 2

Feel The Track’s Testing Program – bringing you the true results of today’s products with honest comments based on real world use.

part 1 - Yacugar shock fitment

Why do we want to change out the stock shock for a more expensive replacement? Normally we are looking for added hydraulic features to provide greater adjustability and improve ride quality. In most cases, that isn’t the case with sport bikes as they have all the adjustability of an aftermarket shock with one exception – adjustable ride height (the ability to make the shock longer by up to 5mm). The most important reason for this decision that most don’t know or understand concerns the range of adjustment for hydraulics. That doesn’t mean the total range of turns or clicks either. In general stock shocks have a range of 1 to 1.5 turns out of 3-4 total turns where changes can be felt and measured whereas aftermarket shocks such as Yacugar can have a range of 2 to 2.5 turns out of 3-3.5 turns. Without getting too technical, that is achieved through the design of the shape of the adjusters themselves.

TECHNICAL INFORMATION

Stock shock features:

  • hydraulic preload adjuster
  • high speed compression
  • low speed compression
  • rebound
  • shock length is 295mm

Yacugar shock features:

  • hydraulic preload adjuster
  • high speed compression
  • low speed compression
  • rebound
  • shock length adjustment +/- 2.5mm
  • shock length is 295mm

When removing a rear shock, it is critical that the bike be locked into position. For the purposes of this article, we used a sport chock and rear stand along with foot peg stands. The bike was rolled into the front stand, then supported on the rear stand. The foot peg stands were sized to the correct height and placed under the mounting brackets for the foot peg, as the foot peg itself bends backwards. Once the foot peg stands were secured, the rear stand was removed.

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The next task was to remove the Leo Vince Corsa system left hand exhaust can in order to provide access to the upper shock mount bolt.  This also included the connector pipe from the exhaust can to the ‘Y’ pipe requiring securing springs to be removed and the clamp mount for the can to the rear sub frame.

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With access to the top shock mount bolt the lock not was removed. The same task was completed with the bottom shock bolt. Both lock nuts were set aside. The lock nut securing the rear shock mount to the frame was then removed. Next task was to remove both the upper and lower shock bolts and then the upper shock mount so that all the shims in place were extracted.  Finally, the stock rear shock was extracted.

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Once the stock shock was removed, the upper shock mount was reinstalled with no shims in place and the lock nut was secured but not set to the correct torque value.

Next, we brought over the Yacugar shock. It is shipped in a very robust container and the shock is set in a foam mould that keeps it firmly centered in the case. On the inside of the case, Yacugar supplies specifications on the shock.

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The shock body is a one piece unit with no hoses attached. The remote preload adjuster can be seen on top of the shock as the smaller cylinder, actuated by hand. The nitrogen reservoir is below it, and to the left of the reservoir are the high and low speed compression adjusters that are color coded:- gold for low speed compression and black for high speed compression. The preselected 11nm spring for my weight comes with 10mm of installed preload and is black  to match the color of the shock body, as is the rebound adjuster which is a dial/round adjuster. Below the rebound adjuster a nut is visible and that is turned to allow the shock to be lengthened or shortened.

The Yacugar shock is installed the same way as the stock shock was removed between the rear sub frame and swing arm. The upper shock bolt is installed first and then the swing arm is lifted to allow the lower shock bolt to be installed by lining up the shock and link plates.

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The upper and lower shock mount bolts were set to the correct torque value, as was the nut holding the shock mount to the frame.

At this point, it is important to measure the length of the shock in place to make sure the data we have is accurate.  Measuring the stock shock this way we found it to be  295mm. TheYacugar shock measured 295mm so we can conclude the Yacugar shock is the same length as stock as installed (in the middle of its ride height range).

Worthy of note is that the stock shock had a total of 7mm of shims between the shock and the frame. In order to get the same geometry, we have 2 options:

  1. Put the original shims back and remove 2mm of ride height from the Yacugar shock in order to get a range of +5mms of adjustment longer
  2. Put 5mm of shims back in to allow a range of positive and negative adjustability

For the purpose of the next tire test 5mm of shims were installed to allow adjustability above and below the current setting to compensate for different rear tire circumferences.

Next, the Leo Vince exhaust was installed, springs attached and the mount secured for the exhaust can to the sub frame.

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Once the Leo Vince exhaust was secured, the R1 was put back in the sport chock in order to set sag and hydraulic damping. We decided to set sag at a total of 27mm. We also reviewed damping settings in checking range of adjustability with a cold shock and ended up with the following hydraulic settings:

  • High speed compression 15 clicks out from closed
  • Low speed compression 15 clicks out from closed
  • Rebound 20 clicks out from closed

The R1 is now ready to go to the track to test the Yacugar shock and see where we end up on all settings based on geometry and internal valving.

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With the shock settings now recorded, the R1 will be fitted with new tires and taken out to the track. During testing, th shock will be reset for all hydraulics to verify the range of adjustability and ride height will also be manipulated to get te best swing arm geometry and edge grip when all the throttle.

More to follow shortly!

part 2 - Yacugar shock test

Yacugar Shock Test THUNDERHILL RACEWAY PARK

DATE: 6/12/2011

TEMP: 73F ambient, surface at 98F

BIKE:  2009 Yamaha R1, 5,800 miles on the odometer

lap 1 straight line braking and acceleration

lap 2 trail braking and mid corner throttle

lap 3 corner exit acceleration

lap 4, fast lap at 90%

Once the 6 laps were completed, the in lap was the same pace as lap 6. The pressure gauge was calibrated earlier to ensure accuracy. Upon entering the hot pit, the bike was parked quickly and hot pressure set at 36 psi front and 25psi rear.

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Session 2: (started immediately after tire pressure was set, total 8 laps)

The goal of session 2 was to evaluate shock response under hard acceleration and Turn 6 was the focus point for the test. It was immediately obvious that the rear of the bike would squat too much so we needed to determine if this was due to preload or ride height. Two turns of ride height were added then removed and 3 clicks of low speed were added and removed. A compromise setting of 1 turn of ride height and 2 clicks of low speed compression were found to provide the best result to eliminate the squat.

Session 3: (started immediately, total 8 laps)

The goal of session 3 was to assess mid corner stability and turn 2 was the corner of choice. Entry speed was a little too fast allowing the front tire to scrub speed, but the throttle was set for a constant radius arc to assess handlebar action side to side/rowing. After a couple of passes through turn 2. Rebound was too slow causing the handlebar to row gently side to side. Rebound was changed 1 click at a time and settled at 23 out for perfectly stable handle bars.

However, changes needed to be made especially with the high speed bumps in 2, 5 and 9 and high speed damping changes shock changes went from 15 to 19 clicks out.

During this session we had the beginnings of rear tire tear: The rear tire was showing initial faint tearing where the bulk of the power was being laid down exiting corners, not where neutral throttle was being applied.

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BREAK TIME for hydration, recollection of thoughts and accurate note taking – 15 minutes

Session 4: (2 warm up laps on the tires and 8 fast laps;- total 10 laps)

The goal of session 4 was to ascertain the source of the rear tire wear and correct it.

BREAK for shock removal and 5mm spacer insertion (took lunch) leaving the shock at stock length of 295mm.

The bike was raised on foot peg stands and the top shock mount bolt loosened with a 23m wrench. The rear stand was used to support the swing arm as the clevis nut was removed and the top shock bolt removed. Spacers were placed on top of the OEM spacer, making a total ride height change of  +5mm. The shock was secured, all nuts and bolts tightened and everything double checked. Forks remained in the same position as a control.

Session 5: (2 warm up laps on the tires and 8 fast laps;- total 10 laps)

The goal of session 5 was to run a complete session with no stops to see if the rear tire would clean up under duress. Pace was constant at the 2:00 to 2:01 lap times to ensure consistency of rider inputs at all times.

The rear tire wear completely cleaned up.

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Session 6: (total 15 laps)

The goal of session 6 was to ride the bike at an increasingly faster pace (fastest lap a 1:58), using the same testing criteria as in earlier sessions to assess braking/steering, mid corner stability and corner exit drive. In running a high number of consecutive laps that would also allow me to get a great feel for the carcass movement under all skill execution conditions.

At the end of the 15 laps, the rear tire wear was perfect!

Final settings:

Free sag at 8mm

Shock length at 295mm plus 5mm spacer

Preload at line # 6

Low speed compression at 15 clicks out

High speec compression at 19 clicks out

Rebound at 23 clicks out

NOTES:

the shock is highly adjustable but over 2 clicks you can really feel a difference so the needle taper is excellent for having changes manifest themselves quickly in the hydraulics

base line valving is excellent for high and low speed:- changes made suggest that high speed may be slightly over valved but still well in range

hydraulic adjuster is a little difficult to use with not much room for the hand and fingers to access the dial especially when hot

shock did not fade at all throughout the entire day even on long stints.

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For the testing period, that was 57 laps x 3 miles = 210 miles.

The rear tire was run another 140 miles and then flipped and run another 170 miles for a total of 520 miles before the tire was replaced. No settings were changed in the shock and tire wear remained the same so the shock hydraulics did not fade when the shock got hot!

Very impressed with the shock especially in regards to valving and how a couple of clicks provide a profound difference in healing tires and in how the shock maintains its level of performance with no fade even on long runs of consecutive laps and after 520 miles.

Addendum:

- the shock now has 2,000 miles on it and the settings have not been changed.